Aquatic & Water Snakes in Alaska (ID + Pictures)

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Alaska mountains
Alaska is predominantly snakeless due to its cold temperatures, which is not great for snakes! Will Buckner / CC BY 2.0

Despite the wonderous and untamed nature Alaska is famous for, snakes are not among the wildlife you might encounter. Together with Hawaii, this state is generally considered snake-free.

The reason Alaska is predominately snake-less is the temperature. Snakes are cold-blooded animals known as ectotherms, which need external heat to move and digest their food — something Alaska does not offer a-plenty! Reptiles are incredibly rare, with some sea turtles and a few cold-adapted amphibians being the only members of the class.

Alaska is famous for its natural areas, where an estimated 900,000 caribou roam. It is the largest state, but simultaneously the least densely populated, providing ample space for diverse and healthy wildlife. The land is separated into a mosaic of ecosystems ranging from tundra to coastal rainforests.

Alaska is home to 32 different so-called ‘ecoregions’, which shape the foundation for its diverse wildlife. Compared to more than 400 threatened or endangered species listed for the lower 48, only 20 Alaskan species are listed in these categories.

The state is home to more than 1,000 vertebrate species, 32 of which are carnivores, making it the most carnivore-rich state, among them, of course, roams the famous polar bear. However, the wilderness of Alaska is also affected by human disturbance and climate change. The average temperature of the state is expected to rise, which will have undetermined effects on the wildlife and environment.

NOTE: The terms ‘semi-aquatic’ and ‘aquatic’ snake are used in this article interchangeably to refer to snakes predominately hunting in aquatic habitats. In this case, ‘aquatic’ does not refer to fully aquatic snake species belonging to the genus Nerodia.

Alaska Water Snakes

1) Common garter snake

Common garter snake
Common garter snakes are dark in color and have three stripes that run along their bodies. Bernie Paquette / CC BY 4.0
  • Scientific name: Thamnophis sirtalis
  • Family: Colubridae
  • Subfamily: Natricinae
  • Other names: Eastern garter snake, garter snake
  • Average adult length: 18 to 26 in (45.7 to 66 cm)
  • Maximum adult length: 49 in (124 cm)
  • Threatened status: Least concern

The common garter snake is the only snake found in Alaska, and while it is not typically counted among ‘water snakes’, they are predominately found near water. It is an indigenous snake with a wide range covering wetlands and aquatic habitats in most of the United States. The common garter snake’s name stems from its characteristic three yellow longitudinal stripes, which presumably resemble traditional garters of men’s garments. They have a dark base color, although some populations exhibit a checkered pattern.

The common garters found in southeast Alaska are considered relics of a former or very small population, and no actual population of snakes has ever been recorded in the state. However, as the climate changes and temperature rise, the snake might be able to fully settle. Since no other snakes occur in the state, misidentification should be impossible. However, note that some snakes observed in Alaska are lost pets.

Common garter snakes hunt in aquatic environments, where they catch pretty much anything they might swallow whole; this includes worms, slugs, and fish. They are opportunistic predators that will also feed on other animals. Common garters are viviparous, which means that they give birth to live young. They are venomous, but the venom itself is so mild, that they were previously considered to be non-venomous. A bite from this species has never resulted in envenomation, however, its sister species, the wandering garter, has on one occasion delivered a documented venomous bite.

Ane Liv B
About the author

Ane Liv B

By day I pursue a PhD in molecular ecology investigating Antarctic fur seal, but I am always keen on sharing my knowledge of all things aquatic. I have years of experience as a scientific educator, conveying complex topics in an accessible fashion.

Read more about Pond Informer.

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